Functions > Utility Functions > Example: String Variable Manipulation
Example: String Variable Manipulation
Use concatenation, substrings and other elementary manipulations of character strings.
Strings for Filenames
1. Define input character strings a and b.
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2. Use the concat function, with the current working directory (CWD) variable, to build path names for file reading functions.
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This variable name can be passed to the READFILE function, for example, or looped through a program to read sequential files from a directory.
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You can also use the format function to concatenate strings combined with variables.
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Substrings and Position
1. Use the substr function to extract the string that starts at position 3 and contains four characters.
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2. Use the strlen function to calculate the length of string c.
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3. Use the search function to locate the starting position of the file extension substring within c.
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4. Write a program to find all occurrences of a substring in a character string.
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5. Use the program to find all occurrences of "in" in the string below.
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Converting Strings to Numbers
1. Use functions rows, cols, IsString, search, concat, substr, strlen and str2num to convert strings to numbers.
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Strings and numbers can be mixed in matrices. You can use lookup functions to search for strings as well as numbers.
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2. Use the program to convert the strings in matrix M to numbers.
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This program uses the str2num to convert strings to numbers. To convert numbers to strings, use num2str.
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3. Change the program so that it sends out an error message if the matrix contains elements that are not strings, and use it.
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In the second call, the functions returned the error message that was specified as a parameter of the error function.
4. Write a program to create a vector from a character string consisting of a numerical sequence. Each number is separated from the preceding number by a comma and a space.
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5. Use the program to convert the following character sequence to a vector.
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ASCII Code Conversions
1. Use the str2vec function to convert a string to a vector of ASCII codes.
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2. Use the vec2str function to convert a vector of ASCII codes to a string.
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3. Use the str2vec and vec2str functions to perform uppercase/lowercase transformations for character strings.
a. Use the str2vec function to define the upper/lower case characters.
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b. Use the str2vec and vect2str functions to define the upper/lower case variables.
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c. Use the previous definitions to convert character string S to lowercase.
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d. Use the previous definitions to convert character string T to uppercase.
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String Functions
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